This invention relates generally to methods and apparatus for attaching soft tissue to bone, and more particularly to anchors and methods for securing connective tissue, such as ligaments or tendons, to bone. The invention has particular application to arthroscopic surgical techniques for reattaching the rotator cuff to the humeral head, in order to repair the rotator cuff.
It is an increasingly common problem for tendons and other soft, connective tissues to tear or to detach from associated bone. One such type of tear or detachment is a xe2x80x9crotator cuffxe2x80x9d tear, wherein the supraspinatus tendon separates from the humerus, causing pain and loss of ability to elevate and externally rotate the arm. Complete separation can occur if the shoulder is subjected to gross trauma, but typically, the tear begins as a small lesion, especially in older patients.
To repair a torn rotator cuff, the typical course today is to do so surgically, through a large incision. This approach is presently taken in almost 99% of rotator cuff repair cases. There are two types of open surgical approaches for repair of the rotator cuff, one known as the xe2x80x9cclassic openxe2x80x9d and the other as the xe2x80x9cmini-openxe2x80x9d. The classic open approach requires a large incision and complete detachment of the deltoid muscle from the acromion to facilitate exposure. The cuff is debrided to ensure suture attachment to viable tissue and to create a reasonable edge approximation. In addition, the humeral head is abraded or notched at the proposed soft tissue to bone reattachment point, as healing is enhanced on a raw bone surface. A series of small diameter holes, referred to as xe2x80x9ctransosseous tunnelsxe2x80x9d, are xe2x80x9cpunchedxe2x80x9d through the bone laterally from the abraded or notched surface to a point on the outside surface of the greater tuberosity, commonly a distance of 2 to 3 cm. Finally, the cuff is sutured and secured to the bone by pulling the suture ends through the transosseous tunnels and tying them together using the bone between two successive tunnels as a bridge, after which the deltoid muscle must be surgically reattached to the acromion. Because of this maneuver, the deltoid requires postoperative protection, thus retarding rehabilitation and possibly resulting in residual weakness. Complete rehabilitation takes approximately 9 to 12 months.
The mini-open technique, which represents the current growing trend and the majority of all surgical repair procedures, differs from the classic approach by gaining access through a smaller incision and splitting rather than detaching the deltoid. Additionally, this procedure is typically performed in conjunction with arthroscopic acromial decompression. Once the deltoid is split, it is retracted to expose the rotator cuff tear. As before, the cuff is debrided, the humeral head is abraded, and the so-called xe2x80x9ctransosseous tunnelsxe2x80x9d, are xe2x80x9cpunchedxe2x80x9d through the bone or suture anchors are inserted. Following the suturing of the rotator cuff to the humeral head, the split deltoid is surgically repaired.
Although the above described surgical techniques are the current standard of care for rotator cuff repair, they are associated with a great deal of patient discomfort and a lengthy recovery time, ranging from at least four months to one year or more. It is the above described manipulation of the deltoid muscle together with the large skin incision that causes the majority of patient discomfort and an increased recovery time.
Less invasive arthroscopic techniques are beginning to be developed in an effort to address the shortcomings of open surgical repair. Working through small trocar portals that minimize disruption of the deltoid muscle, a few surgeons have been able to reattach the rotator cuff using various bone anchor and suture configurations. The rotator cuff is sutured intracorporeally and an anchor is driven into bone at a location appropriate for repair. Rather than thread the suture through transosseous tunnels which are difficult or impossible to create arthroscopically using current techniques, the repair is completed by tying the cuff down against bone using the anchor and suture. Early results of less invasive techniques are encouraging, with a substantial reduction in both patient recovery time and discomfort.
Unfortunately, the skill level required to facilitate an entirely arthroscopic repair of the rotator cuff is inordinately high. Intracorporeal suturing is clumsy and time consuming, and only the simplest stitch patterns can be utilized. Extracorporeal knot tying is somewhat less difficult, but the tightness of the knots is difficult to judge, and the tension cannot later be adjusted. Also, because of the use of bone anchors to provide a suture fixation point in the bone, the knots that secure the soft tissues to the anchor by necessity leave the knot bundle on top of the soft tissues. In the case of rotator cuff repair, this means that the knot bundle is left in the shoulder capsule where it is able to be felt by the patient postoperatively when the patient exercises the shoulder joint. So, knots tied arthroscopically are difficult to achieve, impossible to adjust, and are located in less than optimal areas of the shoulder. Suture tension is also impossible to measure and adjust once the knot has been fixed. Consequently, because of the technical difficulty of the procedure, presently less than 1% of all rotator cuff procedures are of the arthroscopic type, and are considered investigational in nature.
Another significant difficulty with current arthroscopic rotator cuff repair techniques are shortcomings related to currently available suture anchors. Suture eyelets in bone anchors available today, which like the eye of a needle are threaded with the thread or suture, are small in radius, and can cause the suture to fail at the eyelet when the anchor is placed under high tensile loads.
There are various bone anchor designs available for use by an orthopedic surgeon for attachment of soft tissues to bone. The basic commonality between the designs is that they create an attachment point in the bone for a suture that may then be passed through the soft tissues and tied, thereby immobilizing the soft tissue. This attachment point may be accomplished by different means. Screws are known for creating such attachments, but suffer from a number of disadvantages, including their tendency to loosen over time, requiring a second procedure to later remove them, and their requirement for a relatively flat attachment geometry.
Another approach is to utilize the difference in density in the cortical bone (the tough, dense outer layer of bone) and the cancellous bone (the less dense, airy and somewhat vascular interior of the bone). There is a clear demarcation between the cortical bone and cancellous bone, where the cortical bone presents a kind of hard shell over the less dense cancellous bone. The aspect ratio of the anchor is such that it typically has a longer axis and a shorter axis and usually is pre-threaded with a suture. These designs use a hole in the cortical bone through which an anchor is inserted. The hole is drilled such that the shorter axis of the anchor will fit through the diameter of the hole, with the longer axis of the anchor being parallel to the axis of the drilled hole. After deployment in to the cancellous bone, the anchor is rotated 90xc2x0 so that the long axis is aligned perpendicularly to the axis of the hole. The suture is pulled, and the anchor is seated up against the inside surface of the cortical layer of bone. Due to the mismatch in the dimensions of the long axis of the anchor and the hole diameter, the anchor cannot be retracted proximally from the hole, thus providing resistance to pull-out. These anchors still suffer from the aforementioned problem of eyelet design that stresses the sutures.
Still other prior art approaches have attempted to use a xe2x80x9cpop rivetxe2x80x9d approach. This type of design requires a hole in the cortical bone into which a split shaft is inserted. The split shaft is hollow, and has a tapered plug leading into its inner lumen. The tapered plug is extended out through the top of the shaft, and when the plug is retracted into the inner lumen, the tapered portion causes the split shaft to be flared outwardly, ostensibly locking the device into the bone.
Other methods of securing soft tissue to bone are known in the prior art, but are not presently considered to be feasible for shoulder repair procedures, because of physicians""s reluctance to leave anything but a suture in the capsule area of the shoulder. The reason for this is that staples, tacks, and the like could possibly fall out and cause injury during movement. As a result of this constraint, the attachment point often must be located at a less than ideal position. Also, the tacks or staples require a substantialhole in the soft tissue, and make it difficult for the surgeon to precisely locate the soft tissue relative to the bone.
As previously discussed, any of the anchor points for sutures mentioned above require that a length of suture be passed through an eyelet fashioned in the anchor and then looped through the soft tissues and tied down to complete the securement. Much skill is required, however, to both place the sutures in the soft tissues, and to tie knots while working through a trocar under endoscopic visualization.
What is needed, therefore, is a new approach for repairing the rotator cuff or fixing other soft tissues to bone, wherein suture tension can be adjusted and possibly measured, the suture resides completely below the cortical bone surface, there is no requirement for the surgeon to tie a knot to attach the suture to the bone anchor, and wherein the procedure associated with the new approach is better for the patient, saves time, is uncomplicated to use, and easily taught to practitioners having skill in the art.
The present invention solves the problems outlined above by providing innovative bone anchor and connective techniques which permit a suture attachment which lies beneath the cortical bone surface. In the present state of the art, the sutures which are passed through the tissues to be attached to bone typically are threaded through a small eyelet incorporated into the head of the anchor and then secured by tying knots in the sutures. Endoscopic knot tying is an arduous and technically demanding task. Therefore, the present invention discloses devices and methods for securing sutures to a bone anchor without the requirement of knot tying.
In one aspect of the invention, there is provided a bone anchor device for attaching connective tissue to bone, which comprises an anchor body, a plurality of suture retaining apertures disposed in the anchor body, and deployable structure for securing the anchor body in bone. The term xe2x80x9cplurality of suture retaining aperturesxe2x80x9d means at least two, but three suture retaining apertures are employed in the presently preferred embodiment.
A longitudinal axis is disposed along a center of the anchor body, wherein the plurality of suture retaining apertures are spaced axially relative to one another. Additionally, in preferred embodiments, at least two of the plurality of suture retaining apertures are transversely offset from one another relative to the longitudinal axis. Most preferably, a first of the at least two of the plurality of suture retaining apertures is disposed on one side of the longitudinal axis and a second of the at least two of the plurality of suture retaining apertures is disposed on the other side of the longitudinal axis. In other words, the two apertures are in a staggered orientation along the axis, with one on one side of the axis, and the other on the other side of the axis. The advantage of this configuration is that, as the suturing material is threaded through the axially spaced suture retaining apertures, because the apertures are offset from one another transversely, relative to the axis, the suturing material is wrapped in an angular orientation relative to the axis. This permits the suturing material to be wrapped over itself as it is threaded through the suture retaining apertures, in an xe2x80x9cover and backxe2x80x9d fashion, as will be described more fully hereinbelow.
In a preferred embodiment, the aforementioned deployable structure comprises a pair of deployable flaps. The anchor body comprises a substantially planar surface in which the plurality of suture retaining apertures are disposed. In its presently preferred embodiment, the anchor body comprises opposing substantially flat surfaces, wherein the plurality of suture retaining apertures extend through the entire anchor body. A stem extends proximally from a proximal end of the anchor body. At least a portion of a longitudinal slit is disposed in the stem.
In another aspect of the invention, a bone anchor device is provided for attaching connective tissue to bone. The bone anchor device comprises an anchor body having opposing substantially flat surfaces, deployable structure on a proximal end of the anchor body for securing the anchor body in bone; and a suture retaining aperture extending through the anchor body flat surfaces. The suture retaining aperture is disposed distally of the deployable structure.
In yet another aspect of the invention, there is provided a bone anchor device for attaching connective tissue to bone, which comprises an anchor body having a distal end and a proximal end. A stem extends proximally from the proximal end of the anchor body. A deployable flap is disposed on the proximal end of the anchor body, and a notch on the anchor body is disposed at a location joining the anchor body and the deployable flap. The notch is adapted to cause the deployable flap to deploy outwardly when force is applied to a proximal end of the deployable flap by an actuator which moves distally relative to the deployable flap.
In another aspect of the invention, there is provided a bone anchor device for attaching connective tissue to bone. This inventive device comprises an anchor body having a distal end and a proximal end and a stem extending proximally from the proximal end of the anchor body. A deployable flap is disposed on the proximal end of the anchor body. The inventive device further comprises a slit, at least a portion of which is disposed in the stem.
In still another aspect of the invention, there is provided a bone anchor device for attaching connective tissue to bone. The inventive device comprises an anchor body having two opposing surfaces, and a suture retaining aperture disposed in the anchor body and extending through both of the opposing surfaces. A length of suturing material extends through the suture retaining aperture, wherein the length of suturing material is looped about the anchor body and contacts substantial portions of both of the two opposing surfaces. Advantageously, in order to fully lock the suturing material in place on the anchor body, a first portion of the length of suturing material is looped over a second portion of the length of suturing material, the second portion of which lies in contacting engagement with one of the opposing surfaces of the anchor body.
Preferably, a second suture retaining aperture is disposed in the anchor body in axially spaced relation to the suture retaining aperture, wherein the length of suture retaining material is looped through both of the suture retaining apertures.
In yet another aspect of the invention, there is disclosed a method for securing connective tissue to bone. This inventive method comprises a step of securing a first end of a length of suture to a portion of soft tissue to be attached to a portion of bone. A second end of the length of suture is threaded sequentially through a plurality of suture retaining apertures in a body of a bone anchor device so that the length of suture is securely fastened to the bone anchor body. The bone anchor body is placed in a blind hole disposed in the aforementioned portion of bone. Then, structure on the bone anchor body is deployed in an outward direction to secure the bone anchor body in the blind hole.